Centralized traffic controlling system for railroads



Aug. 3, 1937. w. D. HAILES CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS 5 Sheets-Sheet 1 Filed Jan. 17, 1953 1 I I l I I I l I I I I I I I .4 I

ATTORNEY I I I I l I I I I I I I 1 5 3m :2. 38 3: EQ 3 528 w. D. HAILES 2,088,699 CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Aug. 3, 1937.

Filed Jan. 17, 1933 5 Sheets-Sheet 2 i v i mom we" igzrkzR/ v I BY I %a./ ATTo EY Aug. 3, 1937. w D, HAlLEs 2,088,699

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Jan. 17, 1955 5 Sheets-Sheet 3 a Q M MN hv p v M 8+ m u u u m 1 O 3 mm n m :1 3 m 9 i 1 vn f+ m 1'3 1 m v Q NE E mm we: 6 MM n u m .3 mm 3 km a mm m W. D. HAILES Aug. 3, 1937.

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Jan. 17, 1935. 5 Sheets-Sheet 4 'IINVEN ZU ATTORNEY W. D. HAILES Aug. 3, 193 7.

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Jan. 17, 1955 5 Sheets-Sheet 5 e2 lvk (8 m an km Q3 MN 3N n N val mvw m3 1 as L Jl H 3E u v \\I. o M N v n R U um mum m m 1 L n .F v M IFIII .L

33 +6 TS QB Patented Aug. 3, 1937 PATENT OFFlE' CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROAD-S William D. Hailes, Brighton, N. Y., assignor to General Railway Signal Company, Rochester,

Application January 17, 1933, Serial No. 652,177

17 Claims.

This invention relates to centralized traflic controlling systems for railroads and it more particularly pertains to the communication part of such systems.

The present invention contemplates a centralized trafiic controlling system in which communication is established between a central control cities and a large number of outlying field stations, by means of a communication system of the selective coded simplex type. and signals at a plurality of stations located along the railroad track are connected to the control oifice by means of a two-wire communication line circuit.

These switches and signals are under the supervision of an operator at the control omce so that the condition of such switches, signals and various other tramc controlling devices'at the distant locations will be transmitted to the control ofiice, for providing the operator with the necessary information for governing train movements. In a system of this type, a series of impulses forming a particular code combination is transmitted over the line circuit for the Selection of a particular field station and the transmission of controls to the selected station. Similarly, a series of impulses forming a particular code combination is transmitted over the line circuit for the registration of a field station in the control office and the transmission of new indications from the registered station. The control circuits and the indication circuits are so interrelated in the selector type apparatus employed, that controls and indications are transmitted on separate cycles of operation.

In the present invention it is proposed to provide a line battery at the controloiiice as well as a line battery at the end field station. It is proposed to use a line battery at the end field station of considerably higher voltage than the control oiiice line battery. For example, the control oifice line battery may be a 100 volt battery and the end field station battery may be a 200 volt battery.

Either control impulses are transmitted from the control ofiice or indication impulses are transmitted from a field station during any particul ar operating cycle. The control impulses are made distinctive by reason of their polarity for the purpose of transmitting the desired controls. The indication impulses are made distinctive by reason of their polarity and by reason of the strength of current in the line'circuit. Therefore, the capacity of the system of the present The switches invention for the transmission of indications is double that for the transmission of controls.

The system is so organized that irrespective of the simultaneous occurrence of control and indication conditions, only one location is effective 5 to transmit impulses at any one time. For eX- ample, the control ofiice may transmit control impulses over the line circuit duringan operating cycle and during this cycle all field stations are prevented from obtaining access to the communication circuit for transmitting indication impulses. Likewise, when-one ofthe field stations is transmitting impulses to the control office, all other field stations are locked out and the circuits are arranged to guard against the control ofiice breaking in on the line during an indication cycle.

If there are several stored controls and indications awaiting transmission at the end of an operating cycle, the control oflice is given preference and the system functions to transmit all of the waiting controls before a field station can obtain access to the line for transmitting indications.

Irrespective of whether the control office or a field station is impulsing the line circuit, the duration of these impulses is determined in the control office. The polarity of the impulses during the transmission of controls is determined in the control ofiice by selectively connecting the control office battery to the communication line. The polarity of the impulses during the transmission of indications is determined at the station transmitting, by effecting the connection of the end field station battery over the two-wire line circuit extending from the end field station to the station transmitting and at the transmitting station selectively connecting this end station battery to the line circuit extending to the control oifice for providing polar impulses.

The field station transmitting indications also determines the strength of the current in the line circuit extending to the control office by selectively connecting a resistance in the line. In other words, the field station which is transmitting indications is capable of selectively applying any one of four different conditions to the line circuit during each step, while the control ofiice, in transmitting controls, is capable of selecting only one of tWo different conditions to be applied to the line circuit for each step.

These characteristic features of the present invention will be explained more in detail in the following description of one embodiment and various other characteristic features, advantages and functions of the invention will be in part acters that are generally made distinctive either by reason of distinctive exponents representative of their location, or by reason of preceding numerals representative of the order of their operation and in which: i

Fig. 1 illustrates the two-wire line circuit extending from the control office throughan intermediate field station to the end field station, 1

together with certain contacts and relays which cooperate in the control of the line circuit and which are schematically illustrated.

Figs. 2A and 2B, when considered together (with Fig. 2B placed to the right of Fig. 2A) illustrate the apparatus and circuit arrangements employed at a typical control office of a centralized traific controlling system embodying the present invention.

Figs. 3A and 33, when considered together (with Fig. 3B placed to the right of Fig. 3A), illustrate the apparatus and circuit arrangements employed at a. typical field station of a centralized trafiic controlling system embodying the present invention.

The illustrations in the drawings are schematic and abbreviated for the purpose of clearness and simplicity. The detailed operation of the circuits may be conveniently followed by placing the four drawings, Figs. 2A, 23, 3A and 33 together inthe order named, with correspondingly numbered lines in alignment. h

The arrangement of those parts of the syste which are not illustrated in the drawings and their cooperation and connection with the illustrated portions will be set forth in the following general description. After the general description, a detailed description will be given of the transmission of controls from the control ofiice for selecting a field station and for operating controlling devices at the selected station. Likewise, a detailed description will be given of the transmission of indications from a field station for registering such station in the control office and 'for thereafter, selectively operating indi-' cating devices associated with the registered station in the control oflice.

General description The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources ofdirectcurrent and the circuits with which these symbols are used always have current flowing in the same direction. The symbols (3+) and (B indicate connections to the opposite terminals of a suitable battery or other direct current source which has a central or intermediate tap designated (CN) and the circuits with which these symbols are used may have current flowing in one direction or the other, depending upon the particular terminal used in combination with the intermediate tap (ON).

For convenience in describing the operation of thesystem, the two line wires connecting the control oiiice with the stations are identified by referring to them as the stepping line and the return line. The stepping line is the line in which the line relays at the ofiice and at the stations are connected, as Well as the impulsing contacts of the impulsing relay located in thevided and arranged to be selectively connected to 'the stepping and return lines for applying polar impulses during outbound calls. At the end field .station, a line battery F3 is provided of substantially double the voltage of battery OB. This field battery is likewise arranged to be selectively connected to the stepping and return line conductors for providing polar impulses during the transmission of inbound calls. The current flowing over the line circuit from battery F3 is also made high or low in character, by means of selectively connecting resistance units in the line at the station transmitting indications.

In considering the organization of the line circuit illustrated in Fig. 1, it will be understood that additional field stations, when provided, may be connected in the line between the control office and the intermediate field station or between the intermediate field station and the end field control office and its contacts are positioned to' the left when a impulse is applied to the stepping line in the control ofiice. It follows from the above that line relay F will actuate its contacts to the right when potential is applied to the return line from the end station battery and to the left when potential is applied to the stepping line from the end station battery.

A marginal line relay HL of the neutral type is connected in series with the stepping line, this relay having such value and adjustment that it is not picked up when current is flowing from battery OB over the line circuit. This relay is likewise not picked up when current is flowing over the line circuit from battery FB, through a resistance unit such as R indicated in Fig. 1. Relay HL is picked up, however, when such resistance unit is short circuited so that a substantial increase in current fiow from battery FB takes place.

A quick acting line repeating relay FP of the neutral type repeats each energization of the line relay F, irrespective of the polarity of the impulse which energizes relay F. In other words, relay FP is picked up each time the line circuit is energized during a cycle of operations and is dropped between successive impulses. An exception to this operation is during the normal at-rest period when relay F is picked up but relay FP remains down.

Slow acting line repeating relay SA of the neutral type, has such slow acting characteristicsv that it does not drop away between the successive energizations of relay F during ,an operating cycle. It is energized at the beginning of a cycle and remains picked up throughout the cycle, until a predetermined time interval elapses at the end of the cycle. An additional slow acting relay SAP of a type similar to relay SA, is provided for repeating the condition of the SA relay in such a manner that relay SAP is picked up at the beginning of a cycle and dropped at the end of a cycle. 7

The impulses or" a cycle of operations cause the step-by-step operation of a stepping relay bank including relays IV, 2V, 3V, 4V, 5V and LV, together with a half step relay VP. This stepping relay bank is arranged to take one step for each deenergized condition of the stepping line circuit between succeeding impulses of a cycle. In other words, the stepping relays are picked up one at a time during each ofi period. The half step relay shifts during each on period.

An impulsing relay P is associated with the stepping relay bank in order to time space the impulses in the control line in accordance with the actual response of the system. A starting relay STR is arranged to be picked up at the start of each control cycle and dropped at the end of the conditioning period of the control cycle, which occurs before the stepping relay bank begins to operate. Relay STR remains down all through a cycle for the transmission of indications. Office relay OR is normally picked up while the system is in its period of blank or at-rest condition and is dropped during the conditi ning period existing at the start of a control cycle, remaining down until the end of the cycle, Relay OR remains up during an indication cycle.

Polarity control relay PC is a polar, biased-toneutral relay used to selectively connect battery OB to the line circuit during the off periods, in preparation for energizing the line with the proper polarity during the succeeding on periods. Ofiice transfer relay OT is picked up during theconditioning period of a control cycle and remains up throughout the cycle to connect the line conductors to the terminals of battery OB as selected by relay PC.

As typical of the equipment located in the control ofiice, a control machine having a group of control levers is shown. These levers consist of switch machine control lever SML, for the purpose of governing the corresponding track switch at the field station with which it is associated and signal control lever SGL, which is for the purpose of governing the corresponding signals at the field station with which it is associated. A miniature track switch ts corresponds to a particular track switch at the field station. A starting button SE is provided to be actuated subsequent to the proper positioning of the control levers, for initiating the system for the transmission of controls as set up by the levers.

The actuation of lever SML to one position or the other results in the normal or reverse control of the corresponding track switch at the field station. The storing relays associated with the starting buttons and their corresponding CD relays are so interconnected that the momentary depression of the starting button SB is stored by a storing relay (not shown), which in turn picks up the corresponding code determining relay CD of the associated station. The starting button SB is shown connected to relay CD by means of a dotted line instead of the complete circuit arrangement in order to simplify the disclosure.

Irrespective of the number of storing relays which are simultaneously picked up or picked up in rapid succession, only one CD relay may be up during one cycle of operations. The interconnection of the CD and storing relay circuits is so arranged that when several storing relays are upa-t the same time, the corresponding CD relays will be picked up one at a time during successive operating cycles, in an order predetermined by their relative locations in the relay bank, all of which has been completely disclosed in the prior application of N. D. Preston et al., Ser. No. 455,304, filed May 24, 1930, corresponding to Australian Patent 1501 of 1931.

For the purpose of illustrating station registration, a typical pilot relay arrangement is shown in Fig. 2A. The pilot relays lPT, ZPT, 3PT and 4PT are connected to the indication buses so that they may be positioned on the first and second steps of a. cycle when indications are transmitted. Odd numbered pilot relays are shown connected to the indication buses which are selectivel'y conditioned by the polar code combinations, as determined by the positioning of relay F. Even numbered pilot relays are shown connected to the'indication buses which are conditioned by the strength of current code combinations, as determined' by the position of relay HL. It will be understood that additional pilot relay may be provided connected to additional stepping relay contacts, up to the point where sufiicient codes for station registration are obtained. I 7

Station relays 2ST and 6ST are shown in Fig. 2Afor use in registering, in the control ofiice, the station which is transmitting indications. These relays are merely typical of a number of such relays'which would ordinarily be provided, one for registering each individual station. Additional relays similar to relays EST and 6ST would be connected to conductors i, 3, l, 5, 1 and 8, connected to contacts of relay 3PT. Dotted rectangles 50, 6B and. 79 indicate that additional groups of contacts similar to those shown, may be added to the pilot relays for increasing the individual station registering capacity from 8 to H5.

Suitable indication storing relays such as IR, 2R and 3B are provided for storing the various indications transmitted from the field stations, after a station has been registered in the control ofiice by the selection of a station relay. It will be understood that relays IR, 2R and 3R. are merely typical of additional indication storing relays which may be provided for storing additional indications repeated by conditions at the field stations and that the contacts of these indication. storing relays may be connected to lamps or other indication devices.

Field station equipment-The field station illustrated in Figs. 3A and 3B includes a quick acting line relay F of the biased-to-neutral polar type, which relay is actuated to the right by positivecurrent coming over the stepping line from the control office and to the left by negative current over the stepping line from the control office. Rielay FP repeats the impulses in the control line irrespective of their polarities, since this relay is of the quick acting neutral type.

Relay I-IL corresponds to relay HL in the control office, in that it is a neutral type relay, having such an operating value that an impulse of low current value applied to the stepping line is not effective to pick it up. An impulse of high current value applied to the line at the start of a control cycle by connecting the two line batteries in series in the line is efiective to pick up relay HL Slow acting relays SA and SAP are similar to corresponding relays in the control office, being used to define the bounds of each operating cycle. These relays have such characteristics that they are somewhat slower in. picking up than the quick acting relays and are considerably slower in releasing than in picking up.

Each field station includes a lock-out relay LO which is picked up at the station which is sending indications over the communication line. As will be later described, the circuits of this lock-out relay are so organized that in the event that several field stations have new indications to transmit at substantially the same time, the station nearest the end of the line obtains connection to the communication system and other stations are locked out. During succeeding cycles, other waiting stations get their chance to transmit indications and take their turns in accordance with their location withrespect to the control ofiice.

Relay PC corresponds to relay PC in the control ofiice, since it determines the polarity of each impulse applied to the line from battery FB, when the station with which this relay is associated is transmitting. Relay CO determines the strength of current of each impulse applied to the line circuit from battery FB when the station with which this relay is associated is transmitting. These two relays are of the polar magnetic stick type.

' Start relay STR is picked up at the field station to start an indication cycle. After the conditioning period this relay drops and remains down during the remainder of the cycle. Relay S'IR stays down during a control cycle. Field transfer relay PI is picked up during the conditioning period of an outbound cycle and remains up until the end of this cycle. This relay remains down during an inbound cycle when indications are being transmitted. Relay FR is of the slow releasing type and is provided to introduce a time delay in the first ofi or conditioning period when indications are transmitted, to permit certain other relay operations to take place as will be later described in detail. End station transfer relay ET is provided at the end field station only and serves the purpose of normally connecting the end station battery to the line circuit, removing this battery at the start of an outbound cycle and placing a short circuit across the line conductors to form a closed circuit for the oflice battery during such a cycle.

A stepping relay bank including relays IV 2V 3V 4V 5V and the associated half step relay VP is provided, these relays operating in synchronism with corresponding relays in the control ofiice, so that they take one step for each deenergization or off period of the line circuit for marking off the steps of the cycle. Pilot relays IPT and 2PT and a station relay ST operate in a manner similar to corresponding relays located in the control ofiice, except that these relays are controlled by polar impulses only, and are conditioned during control cycles. It Will be understood that additional pilot relays and additional station relays may be provided and connected in an obvious manner as the size of the system demands.

A track switch TS is operated by a switch machine SM of any suitable type. The position, locked and unlocked conditions of the track switch may be repeated by the usual switch repeating relay WP This switch repeating relay has its contacts connected to the indication circuits so that the condition of the track switch is transmitted to the control oflice. The switch machine SM is remotely controlled by the operator in accordance with the position. of lever SML of Fig. 2A, with such control locally repeated at the field station to the switch machine by relay SMR Suitable signals are provided for governing trafiic over the track section illustrated .in Fig. 33. Their control is in accordance with suitable automatic signaling, in cooperation with the position of the signal control lever SGL in the control oihce as repeated by relays SG and DR A track relay T is provided to register a change in the condition of the detector track section with which this relay is associated. Indication code circuits are connected to contacts of relay T and it will be later described in detail how the positions of relays such as T and WP are repeated to the control oflice by means of code combinations made up of polar impulses of high and low current strength.

Relay CH is the usual change relay provided at each field station for registering a change in the traiiic controlling devices at the associated station, so that the system will be automatically started through a cycle of operations for the 7 its back contact I58 by the interruptionof its holding stick circuit, when a change in position of switch machine relay WP track relay T or any other suitable relay takesplace. Such a circuit arrangement is disclosed in De Long et al. Patent No. 1,852,402 issued April 5, 1932. Relay CH will register a change inone or more of a large number of devices and will initiate indication cycles as long as there are new indications to be transmitted.

It is believed that the nature of the invention, its advantages and characteristic features may be best understood by continuing the description in a manner relating to the detailed operation of the system.

Operation comparatively low value, (due to the inclusion of resistance R) relays HL, HL H11 etc. are partially energized, but do not receive sufiicient energy under this condition to pick up their contacts.

A cycle of operations for the transmission of controls is started by initially changing the degree of energization of the line circuit from a low to a high value. A cycle of operations for the transmission of indications is started by initially changing the degree of energization of the line circuit from a low to a zero value.

The circuit for normally energizing the line conductors may be traced from the side of battery FB, back contact l5! of relay ET conductor H2, back contact I52 of relay L0 conductor I0, back contact [3 of relay OT, back contact M of relay STR, resistance R, normally closed front contact l5 of relay OR, back contact I6 of relay STR, back contact ll of relay OT, winding of relay HL, winding of relay F, back contact l8 of relay P, conductor II, windings of relays and F back contact I53 of relay L0 back contact I54 of relay STR conductor.l20, windings of relays BL and F and back contact I55 of relay ET to the terminal of battery FB. It will be understood that the above traced normally energized line circuit extends through contacts and relay windings at other field stations similar to those illustrated in Fig. 1.

Relay OR of Fig. 2B is normally energized over tending from (CN), winding of relay VP, back contact I38 of relay SA and back contacts 40, 4|, 42, 43 and 44 of the five stepping relays in series to (B), which normally positions relay VP to the right. Relay VP is normally energized and positioned to the right by a circuit extending from (CN), back contact 248 of relay SA winding of relay VP conductor I'M and back contacts I13, I12, Ill, I10 and I93 of the five stepping relays to (B).

Relay OR of Fig. 2B is normally energized over a circuit extending from back contact I2 of relay SA, back contact 25 of relay HL and winding of relay OR, to With the exception of relays WP T and CH of Fig. 33, all other relays are normally deenergized.

Manual start.With the system at-rest, the operator can initiate a cycle for the selection of a particular station and the transmission of desired controls to the selected station. For example, if he desires to operate the track switch TS he properly positions control lever SML and then actuates starting button SB. It is to be noted that the operator may precondition the control lever SML (and other similar levers such as SGL) as desired, without the transmission of controls until the starting button SB is actuated. However, such an arrangement is to be considered as merely typical, since the system may readily be arranged to be initiated upon the actuation of a control lever without the need of operating a starting button. The latter plan is shown, for example, in the prior application of N. D. Preston, Ser. No. 573,079, filedNovember 5, 193 1, corresponding to Britsh Patent 406,418.

The actuation of button SB while the system is at-rest causes the energization of code determining relay CD. Relay CD closes a circuit for picking up relay STR extending from back contact 2| of relay SA, winding of relay STR, conductor 22 and front contact 23 of relay CD, to Relay STR closes a temporary stick circuit for itself extending from back contact 24 of relay SAP, front contact 25 of relay STR and winding of relay STR over the remainder of the above described pick-up circuit, to

The actuation of relay STR causes the line circuit to be energized with an initial impulse of high current value. This high current value is due to the connection of the office battery OB and the field battery in series aiding relation to the line circuit. It will be recalled that the stepping line was normally energized with the side of battery FB extended to back contact I6 of relay STR. When relay STR picks up, its front contacts l4 and I6 are closed and these back contacts are opened. This results in connecting the side of battery OB to the return line conductor Ill and the side of this battery to the stepping line conductor I 5. Therefore, these two line batteries are connected in series with the line circuit and in series with each other in aiding relation as clearly indicated in Fig. 1.

Assuming that battery FB is double the voltage of battery OB, this series aiding connection results in a current flow over the line circuit which is approximately three times the normal v value. The polar relays such as F, F and F in the line circuit remain actuated to their right hand positions and the marginal line relays such as HL, HL and HL are picked up by this increase in current flow.

The actuation of relay HL closes a circuit for picking up relay SA which extends from contact 263 of relay F in its right hand position, front contact 2i of relay HL and winding of relay SA,

to its winding extending from contact 26 of relay F in its right hand position, front contact 28 of relay SA and winding of this relay, to It will be noted that this substitute circuit for relay SA is intermittently opened by the release of relay F during the off periods, but the impulses follow each other in such rapid succession that relay SA is reenergized before it has time to drop its armature.

The picking up of relay HL opens the pick-up circuit of relay OR at back contact 26 before the stick circuit of relay OR is established at front contact 82 of relay SA, with the result that relay OR drops and remains down during the remainder of this cycle.

Relay OR, in dropping, opens the indication executing circuits at front contacts 36 and 3! so that the indication devices can not be positioned during the positioning of relays F and HL during an outbound cycle. Relay OR opens the normal bridge across the line conductors including resistance R, at its front contact I5.

The actuation of relay SA closes a circuit for picking up relay SAP which extends from front contact 32 of relay SA and winding of relay SAP, to Relay SAP is slow to pick up, so that it will not close the pick-up circuit for the first stepping relay IV at its front contact 33, before relay FP gets up and opens this pick-up circuit at its back contact 34.

The circuit for picking up relay FF is effective when relay SA picks up and extends from contact 39 of relay F in its right hand position, winding of relay FF and front contact 29 of relay SA, to

The actuation of relay SAP closes a pick-up circuit for relay OT extending from front contact 2! of relay SA, back contact 35 of relay OR, front contact 35 of relay HL, winding of relay OT and front contact 31 of relay SAP, to Relay OT closes a stick circuit for itself which includes the above described circuit, with front contact 35 of relay I-IL bridged by front contact 38 of relay OT. This stick circuit is effective to l0 Relay SA closes a substitute circuit to maintain relay OT picked up throughout the" During the above described conditioning at the control ofiice, similar operations at the field Sta-" tions have been effected. For example, the picking up of relay HL with relay F positioned to the right, closes a circuit for picking up relay SA which extends from contact HM of relay F in its right hand position, front contact I94 of relay HL and winding of relay 8A to Relay SA closes a substitute circuit to its winding extending from contact I9I of relay F in its right hand position, front contact I95 of relay,

ing of relay F1, to

8A and vn'nding of relay' SA to It will be noted that this substitutecircuit is intermittently opened by the release of relay F during the off periods, but the impulses follow each other in such rapid succession thatrelay SA is reenergiz ed before it has time to drop its armature.

A circuit is now closed for picking up relay FT which extends from back contact I96 of relay SA front contact I91 of relay HL and wind- It will be noted that this pick-'upcircuit for'relay FT is interrupted at back contact I96 when relay SA picks up, but since the circuits of these two relays are closed at substantially the same time and since the pickup time of relay SA is considerably longer than the pick-up time of relay FT the latter relay ,actuates its contacts before relay SA is picked up. 'The actuation of relay FT establishes a stick cir- "cuit'for itself extending from make-beforebreak front contact I 96 of relay SA front contact I98 and winding of relay FT to A circuit is closed for picking up relay FP extending from front contact I99 of relay FT contact 200 of relay F in its right hand position and winding of relay FP to A circuit is closed for picking up relay SAP extending from front contact 20I of relay SA front contact 202 of relay FT and winding of relay SAP to Relay VP is maintained in its right hand position by means of a circuit extending from (CN), front contact I15 of relay FP winding of relay VP conductor I14, back contacts I13, I12,

, I'll, I19 and I93 in series of stepping relays V 4V 3V 2V and IV respectively, to (B).

'Obviously, relay VP was already in its right hand position as previously mentioned so the above described circuit does nothing more than energize the winding of this relay.

Referring to Fig. 1 and recalling that relay F was held in its right hand position and relay HI. pick up (at the end station), circuits are closed for picking up relays SA and SAP which circuits are similar to those at the station illustrated in Fig. 3A. A circuit is established for picking up relay FT before relay SA has actuated its contacts, said circuit extending from back contact 250 of relay 8A front contact 25I of relay HL and winding of relay FT to The actuation of the contacts of relay SA closes a stick circuit for relay F'I' at the make-beforebreak front contact 250, by way of front contact 252 of relay F'I to its winding. A circuit is also closed for picking up relay ET which extends from (+),front contact 253 of relay FT front contact 254 of relay SAP front contact 255 of relay 8A and Winding of relay ET to Since this circuit-remains closed throughout the cycle, relay ET remains up, disconnecting battery F3 from the line conductors and placing a short circuit across these conductors at the end of the lineduring this cycle.

The dropping of relay S'I'R in the control office and the resulting opening of the line circuit at its contact I6 as above described advances the system out of the conditioning period into the first off period. Briefly, the system is initiated into a cycle of operations forthe transmission of controls by increasing the normal energization of the line circuit approximately three-fold, after which: the line is deenergized. This is brought about during the conditioning period by the picking up and dropping of relay STR.

Line impulsing and stepping relay opera.tiom. Although the stepping and impulsing operaions will be more particularly directed to Figs. 23,

:3A and 313, it will be understood that similar operations take place at other stations along the line. With the line circuit opened as above described for advancing the system into the first off period, relays F, HL, F and HL restore to their deenergized positions. Relay HL is slightly slow in releasing, due to the fact that its lower winding is short circuited by way of a circuit including its front contact 45 and front contact 46 of relay FP. The reason for this will be pointed out in connection with the transmission of indications.

Relay F opens the circuit of relay FP at contact 39, allowing relay FP to drop, which in turn closes a circuit for picking up relay IV extending from back contact 41 of relay OR, front contact 33 of relay SAP, front contact 48 of relay SA, back contact 34 of relay FP, contact 49 of relay VP in its right hand position, back contact 5| of relay 4V, back contact 52' of relay 2V and winding of relay IV, to Relay IV closes a stick circuit for itself which extends from back contact 41 of relay OR, front contact contact I69 of relay VP in its right hand position, conductor I6I, back contact I62 of relay relay 4V back contact I63 of relay 2V and winding of relay IV to Relay IV establishes a stick circuit for itself which extends from front contact I56 of relay F'I front contact I5! of relay SAP front contact I 58 of relay SA stick conductor I64 and front contact I65 of relay IV to the winding of relay IV The operation of relay IV closes a circuit for relay PC from (B) (Fig. 2A), code jumper 55 in its full line position, front contact 56 of relay CD, No. 1 control bus 51, front contact 58 of relay IV, back contact 59 of relay 2V, back contact 6| of relay 3V, back contact 62 of relay 4V, back contact 63 of relay 5V, back contact 64 of relay OR and winding of relay PC, to (CN) The current flowing in this circuit is in such a direction up, the end station battery F3 is not included in the line circuit. The two line conductors are connected together through front contacts I5I and I55 of relay ET The energization of the line is effective to pick up relays F and F but since the current flow at this time is of comparative low value, relays HL and HL remain down. Relay F again closes the pick-up circuit of relay FF and relay F again closes the pick-up circuit of relay FP the circuits of which were previously traced.

The actuation of relay FP closes a circuit for positioning relay VP to the left, which circuit extends-from (B+), front contact I93 of relay IV back contacts I10, I'II, I12 and H3 of relays 2V 3V 4V and 5V respectively, conductor II4, winding of relay VP and front contact I15 of relay FP to (CN).

The actuation of the contacts of relay FP closes circuit which is effective to actuate relay VP to back contacts 53, 42, ll and it of relays 2V, 3V, AV and 5V respectively, front contact i9 of relay FF and winding of relay VP, to (ON).

A circuit is now closed for picking up impulse relay P which extends from contact 55 of relay VP in its left hand dotted position, upper winding of relay P, front contact 65 of relay IV, back contacts 6?, 63, 59, ii and E2 of relays 2V, 5V, 4V, 5V and LV respectively and front contact l5 of relay SAP, to The actuation of relay P opens the line circuit at its back contact I8 which is effective to again drop relays F, FP, F and PP.

In the control office, relay 2V is now picked up over a circuit extending from back contact 4! of relay OR, front contact 33 of relay SAP, front contact if; of relay SA, back contact 34 of relay PP, contact 2-9 of relay VP in its left hand dotted position, back contact i l of relay 3V, front contact 35 of relay W and the winding of relay 2V, to Relay 2V closes a stick circuit for itself by way of its front contact 16 to potential which is connected to stick conductor 53.

At the field station, relay 2V is picked up by means of a circuit extending from front contact l56 of relay FT front contact l5! of relay SAP front contact i58 of relay SA back contact 655 of relay FP contact Hi) of relay VP in its left hand dotted position, conductor H56, back contact lBl of relay 3V front contact H58 of relay W and the winding of relay 2V to Relay 2V establishes a stick circuit for itself by way of its front contact ME? to potential which is now connected to stick conductor 0%.

Relay P in the control ofiice is now dropped due to the fact that the above described pick-up circuit through its upper winding is interrupted at back contact Ell of relay 2V. The release of relay P again closes the line circuit at its back contactl8, which is effective to pick up relays F, FP, F and FP Relay VP in the control ofiice is now positioned to the right by means of a circuit extending from (13-) front contact 33 of relay 2V, back contact 42 of relay 3V, back contact M of relay 4V, back contact id of relay 5V, front contact l9 of relay PP and winding of relay VP, to (CN) At the field station, a similar circuit is effective to position relay Vl? to the right which may be traced from (3-), front contact no of relay 2V back contact ill of relay 3V back contact N2 of relay 3V back contact I13 of relay 5V conductor l'l l, winding of relay VP and front contact N5 of relay FP to (CN).

The shifting of relay VP in the control ofi'lce is effective to again pick up relay P by way of a circuit which extends from contact 65 of relay VP in its right hand position, lower winding of relay P, front contact 67 of relay 2V, back contacts 68, 69, H and E2 of stepping relays 3V, 4V, 5V and LV in series and front contacts 13 of relay SAP, to

It is believed that the above examples reciting the circuit arrangements for picking up the firsttwo stepping relays in the control o-fiiceand at the typical field station, as well as the shifting of the VP relays at these locations, are sufficient to indicate the manner in which the stepping relay banks and the line impulsing relay fume-- tion. It will be understood that the additional. stepping relays 3V, 4V and 5V as well as relays- 3V1, 4V1 and-5V1 operate in synchronism on the 1B ofrelay PC, but irrespectiveof the polaritysucceeding steps, in the same manner as has been described in connection with the first two stepping relays. It will be observed that the stepping relays are picked up in rotation during successive off periods and the half step relays are shifted during succeeding on periods. These half step relays are positioned to the left after each odd off period and tothe right after each even off period.

Polarity selection of impulses for controls. As above pointed out, during a .cycleof operations started manually from the control oirlce, .the normally low value of current energization of the line circuit is increased during what is conveniently termed the conditioning period.

This high current impulse fixes the cycle as a control cycle, by causing the release of relay OR.

and the picking up relay OT, as well as the picking up and the release of relay STR in the control ofiice.

Assuming that the stepping relays pick up as above described, the first control impulse to be applied to the line after the first off period, (which follows the conditioning on period) is determined by the connection of code jumper 55. For example, with code jumper 55 connected to (B-) as shown in Fig. 2A, a circuit is completed for actuating relay PC to the left, which was previously described. This conditioning circuit of relay PC is effective during the off period, since relay IV is picked up when the line circuit is deenergized.

When the line is next closed, the stepping line conductor will be energized from the terminal of battery 03, contact ll of relay PC in its left hand dotted position, front contact ll of relay OT, windings of relays HL and F and back contact l8 of relay P to the stepping line co-nductor II. The return path is by way of conductor it, through front contact l3 of relay OT. and contact 18 of relay PC in its left hand dotted position, to the terminal of battery OB.

Should jumper 55 be connected in its alternate dotted line position which leads to (13+), then the conditioning circuit for relay PC would, result in actuating this relay to the right, which would be effective to reverse the battery connection to the line for energizing the stepping line with a potential. Therefore, the selective connection of jumper 55 to (13+) or (3+) selectively conditions (during an off period) the polarity with which the stepping line is to be energized during the succeeding on period.

scribed circuit to relay PC. With jumper selectively connected to (13+) or (13-), relay PC is positioned for selectively energizing the' line circuit following the second off period.

It .will thus be seen that the potential selected by front contacts 58 and 59 of relays 5V and 2V respectively, causes the actuation of the polar contacts of relay PC to a proper position for determining the desired polarity of the next succeeding impulse to be applied to the control 'line upon the closure of back contact 18 of impulsing relay P.

Upon the closure of this back contact l8, line irelays F and F are energized with a polarity dependent uponthe position of contacts 11 and of the impulse, the line repeating relays FF and FP are immediately picked up.

When relay 3V picks up during the third off period, the circuit of relay PC is extended through fro-nt contact 6| of relay 3V, control code bus88, front contact 8| of relay CD, to contacts of the switch .machine lever SML. If the contacts of lever SML are in a right hand position, (B+) is applied to the code sending relay PC. With the contacts of the lever in their left hand dotted positions, (B) is applied over the above described circuit to relay PC- When the system takes its fourth step, relay 4V extends the circuit of relay PC by way of front contact 62 of relay 4V, code control bus 89 and front contact 19 of relay CD to contact 9 on signal lever SGL. It will be obvious that at stop full line position of the lever and the proceed dotted line positions of these contacts will be repeated by relay PC in a manner which has already been described.

Signal lever SGL, with its contact 99 in a right hand dotted position, extends a circuit from (3+), through front contact 84 of relay vCD, control code bus 82 and front contact 63 of relay 5V to the winding of relay PC. With lever SGL in its 'left hand dotted position, this circuit to relay PC extends from (B') From the above it will be observed that different code combinations, on a choice of two per step, or may be chosen for selecting field stations, by arranging the connections of jumpers55 and 85 each in either one of two positions. It will be obvious that other code jumpers may be provided for additional steps which would result in a selection of an increased number of stations. It will also be understood that additional steps may be provided for selecting additional control devices similar to levers SML and SGL and that the positions of such devices may be repeated by relay PC during additional steps of the stepping relay bank.

Transmission of controls-It will be assumed that relay IV at the station shown in Fig, 3B is up and that the control line is energized with a impulse from battery OB as above explained, this impulse causing relay F to actuate its contacts to left hand dotted positions. An execution circuit is closed during this period which governs pilot relay IPT This circuit extends from (B), contact I16 of relay F in its left hand dotted position, front contact I11 of relay FI conductor I18, back contacts I19, I80, I8I and I82 of stepping relays 5V 4V 3V and 2V respectively, front contact I83 of relay IV and lower winding of relay IPT to (B). Since the same potential is applied to both terminals of this winding, relay IPT remains down.

In'the event that the first code selecting impulse applied to the line is then relay F would close a circuit from (B+), contact I16 in its right hand position and over the remainder of the above described circuit to the lower winding of relay IPT In this case, opposite poten- 5 tials applied to the terminals of this relay winding result in the relay picking up. When it is picked up, it closes a stick circuit for itself during the remainder of the cycle which extends from front contact I56 of relay FI' front contact I51 of relay SAP front contact I58 of relay SA conductor I 64, front contact 206 and upper winding of relay IPT to When relay 2V is picked up, a circuit is completed which governs pilot relay 2PT. Since the second code impulse in the line circuit was assumed which actuated relay F 'to the right, the circuit connection to relay 2PT extendsfrom '(B+), contact I16 of relay F in its right hand position, over the above described circuit including conductor I18 and now through front contact I82 of relay 2V and through the lower winding of relay ,2PT to (B). Since opposite potentials are applied to this winding, relay 2PT picks up and closes a stick circuit for itself extending from contact I56 of relay FT front contacts I51 and I58 of relays SAP and SA respectively, stick conductor I64, front contact I84 and upper winding of relay 2PT to This stick circuit is effective to hold relay ZPT up throughout the cycle.

When relay 3V is picked up, a circuit is completed for picking up station relay ST which extends from front contact I85 of relay 3V back contact I86 of relay IPT front contact I81 of relay 2PT code jumper I88 and winding of relay ST to- It will be apparent that jumpers similar to I88 at other stations will be connected to the other contacts of relays similar to 2PT for selectively picking up the proper station relays at these other stations.

An execution circuit is closed for controlling switch machine control relay on the third step, which extends from contact I16 of relay F selectively connected to (3+) or (13-) as determined by the polarity of the code impulse during this step, front contact I11 of relay FT conductor 518, back contacts I19 and I88 of relays V and 4V respectively, front contact I8I of relay 3V front contact I89 of relay ST and winding of relay SMR to (CN). Relay SMR actuates its polar contact ISO to a right or left hand position, depending upon whether (B+) or (3-) potential respectively is applied to its winding.

Contact I90 of relay SMR', governs the operation of the switch machine. Since this local switch machine circuit forms no part of the present invention and since it has been disclosed in numerous applications, the detailed circuit is not shown, but instead the relay contacts are indicated as being connected to switch machine SM by a dotted line. Inbrief, the positioning of control lever SML determines the polarity applied to the switch machine control relay SMR which in turn governs the operation of the switch machine.

The transmission of additional controls is effective on succeeding steps of the stepping relay bank at the field station, for selectively positioning other function control relays at the selected station such as relays SG and DR which relays are effective to control their associated signaling devices. The detailed circuits of this control are not shown since they are well understood.

The transmission of controls continues until the predetermined number of steps have been taken, which by way of example has been specifically illustrated as including five steps, two of which are employed for station selection and the other three for governing the controls at theselected station. I

Stepping relay 5V in the control office is picked up on the fifth off or deenergized period of the line circuit, at which time relay VP is in its right hand position. Relay P now drops to startthe succeeding on period. Relays F and FF now 1 pick up and a circuit is closed for picking up relay LV extending from back contact 41 of relay OR, front contact 33 of relay SAP, front contact 7 48 of relay SA, front contact 34 of relay FP, front contact 88 of relay 5V and winding of relay LV,

to Relay LV closes a stick circuit for itself by way of its front contact 83 to stick conductor Relay VP shifts to its left hand position at this time, due to the fact that a circuit is closed during the fifthfon period from (B+), front contact 40 of relay 5V and front contact I9 of relay FP, to the winding of relay VP. With relay VP in its left hand position and with relay LV picked up, a circuit is closed for picking up relay P which extends from contact 65 of relay VP in its left hand dotted position, upper winding of relay.

P, front contact 12 of relay LV and front contact 13 of relay SAP, to The reason relay LV is slow acting will be explained in'connec'tion with stored start conditions.

The picking upof relay P opens the stepping line conductor II at its back contact I8 and since'there'are no more stepping relays to be operated, this circuit remains effective for a comparatively long interval of time, so that relay F remains down long enough to allow slow acting relay SA tobe released. The release of relay SA causes the release of relay SAP. Relay SA at the field station is released at substantially the same time as the corresponding relay in the control oflice, due to the dropping of relay F Relay SAP is not released during this period because of. a stick circuit which extends from contact l9l of relay F in its deenergized position, front contact I92 of relay SAP and winding of this relay, to

When the line is energized with a low current value (which occurs to place the system in its normal condition) relay F is positioned to the right, which opens its center position contact I! included in the above described stick circuit of relay SAP and this results in dropping relay SAP The purpose of this circuit arrangement for holding relay SAP in its picked up position until the line is energized at the end of the cycle when the system is changed to its normal at-rest condition, is to enable the control oflice to obtain access to the communication system for.

transmitting all of its waiting controls before permitting a field station to break in on the line. This feature will-be discussed more in detail later.

With the release of relays SA and SA the stick circuits of the stepping relays at the control office and at the field stations are interrupted'and these stepping relays are restored to normal. During the transmission of controls the line is energized each time with a low current value (after the conditioning period) with the result that relay HL (and. similar relays) do not pick up. I

Automatic start.The system may be initiated into a cycle of operations from its normal period by an automatic change in conditions at a field station. Such initiation may be due to a change in traffic conditions or to the operation of a traffic controlling device to a new position as a result of controls transmitted from the control office.

' The stick circuit'for change relay CH (Fig. 3B) is carried through front and back contacts of the track relay T ,'the switchmachine repeating relay WP and like contacts of other'traffic controlling devices located at the field station. Irrespective of the particular 7' change which occurs, the shifting of the relaycontacts of a relay such as relay T interrupts the stick circuit of relay CH and this latter relay is dropped. The dropping of relay CH closes a pick-up circuit for start relay STR extending fromback contact I50 of relay CH conductor 203, back contact 204 of relay SAP back contact 205 of relay FR back contact 201 of relay HL winding of relay STR and back contact 208 of'relay FT to Relay STR closes a'substitute circuit for itself by way of its front contact 209, which is independent of contacts 205 and 201 of relays FR and HL respectively. The purpose ofthis sub stitute circuit is to maintain relay STR in its picked up position after the operation of relay FR which occurs shortly after the picking up of relay STR It wil1 be recalled that the line circuit is normally energized with a low current value when the above mentioned operations take place. The picking up of relay STR opens the stepping line conductor at back contact I54 which is effective to deenergize the line circuit to start the indication cycle; Relays F and F now release and relay F closes a circuit for picking up relay FR which extends from contact I9I of relay F in its deenergized position, back contact I92 of relay SAP back contact 2I0 of relay'SA and winding of relay FR to Relay FR. closes a temporary stick circuit for itself which extends from contact I9I of relay F in its deenergized position, back contact I92 of relay SAP back contact 2 of relay LO ,-front contact 2I2 of relay FR andwinding of relay FR to The circuit is now closed for picking up relay SA which extends from front contact 2I3 of. relay FR and winding of relay SA to The operation of relay SA opens the pick-up circuit of relay FR at back contact 210 but at this time relay FR remains energized due to its stick circuit. Relay SA opens the pick-up circuit of relay FT at back contact I96 so that relay FT remains down during this cycle.

A circuit is now closed for picking up lock-out relay LO which extends from the terminal of battery FB, located at the end field station, back contact II of relay ET conductor II2, front contact 2I4 of relay SA upper winding of relay L0 resistance R ,'front contact I54 of relay STR conductor I20 and back contact I55 of relay ET to the terminal of battery FB. Relay LO closes a stick circuit for itself which maintains this relay in its picked up position throughout this cycle, which circuit extends from front contact 2I5 of. relay SA front contact 2 I6 and lower winding of relay L0 to Stepping relay I V is picked up at this time by means of a circuit extending from back contact I56 of relay FT front contact I58 of relay SA back contact I59 of relay FP contact I60 of relay VP in its right hand position, conductor. I6I, back contact I62 of relay 4V back contact I63 of relay 2V and winding of relay IV to Relay IV establishesa stick circuit for itself which is effective during this cycle and which extends from back contact I56 of relay FT front contact I58 of relay 6A stick conductor I64, front contact I65 of relay IV and winding of. relay IV to The picking up of relay L0 opens the stick circuit of relay PR at its back contact 2 and since the pick-up circuit of relay PR is open at back contact 2I0 of relay SA relay FR deenergizes and due to its slow acting characteristics, restores its contacts to their deenergized positions after a comparatively long interval of time.

At'the time relays FR and SA were picked up, a circuit was established for energizinglrelay SAP which extends from 1+), front Contact 21H of relaySAL front contact 2 l1 offrelay FR}, back {contact 218 of relayLO and windin'g of relay SAP to Shortly after this, relay L0! is picked up which opens this pick-up circuit for relay SA]? at back contact 218, so that relay SAP .does not have time topickup its armature. This guards against relay SAP picking upand releasing relay S'IR too soon, which would not give sufiicient time during; this, first off or V conditioning period for conditioning. all the necessary relays.

When relay FR is released, the circuit for en;

ergizing relay SAP is again closed, this time,

from front contact 2! of relay SA. ,back contact 2|! of relay FR frontcontact 2 l 8 of relay L0 and winding of relay SAP to This circuit is effectivelfto pick up relay SAP.

Belay SAP establishes a substitutecircuit to its winding by wayof its front contact I 92 and contact Isl of relay F in its deenergized position, 'which circuit is effective to energize relay SAP} each time the line .is deenergized. Since the 7 impulses in the line which result inpicking up relay-F follow each other in rapid succession, this substitute circuit for relay SAP is not broken for suflicient time to allow it to be released during impulsing of the line.

The dropping of relay FR opens the pickup circuit of relay SA at front contact 2l3 but relay SA remains energized by way of a circuit 'which extends to at contact l9l of relay 'F in either of its picked up positions, which circuit is closed at such a frequency during im pulsing that relay SA} does not have time to drop its contacts. V V V V Relay STR is released whenrelay SAP picks up and opens its back contact 204, This results in energizing, the line circuit and advances the system into the first on period; The polarity with which the line is energized and the degreeof energization is controlled by means of the indication selectingcircuit which'will be later described. a v a v I 3 While all this has been going onat the field station, similar operations have been taking place at the control 1 oiiice; Relay F ,(Fig 2B) is dropped at the time theline circuit istopened at the beginning of the conditioning period and a circuit is established for picking'up relay -S A which extends from contact 26" of relay F in its deenergized position, back contact 90 of rel y SAP and winding of relay SA, to RelaycSA establishes its sustaining stickfcircuit which hasbeen previously described. Relay STR 1 remains' .down during this cycle due to the fact that its pick-up circuit is open at back contact 2| of relay SA. Relay OR remains'up because itsstick circuit including its:fr'ont'-contact- 9| is closed at'front contact vI2 of relaySA before its pick-'uprcircuit is opened. Acircuit is closed for picking up relay SAP which has been .pre-. viously described. The circuit for picking up relay IV likewise has been previously described.

At the end field 'station,'.relay F? is picked up in synchronism with relays F andjF and 're-' lays SA and SAP are-picked up by. means, of circuits similar tothose illustrated andexplained in connection with the station of Fig. 3A, Re; lay IF'I remains .down, which keeps the pickup circuitof relay ET open so that thislatte r relay cannot pick up during an indication cycle.

Thisresults in battery F'B being connected tothe line circuit extending back to the station whichis transmitting, ;with;the terminal of this of relay L0 to one set of contacts of relay-RC while the terminal' ofthls battery .iSTCOnnected bywayiof front contact I53 of relay L0 to the other set of contacts of relay PC}. l a

,It should be mentioned at this time that the purpose of resistance R? is to compensate for. V V

the; resistance removed from the line extending to the control office when. a station connects its lock-cut relay across the line conductors leading toethe'end station battery. This resistance increaseSIin value at stations farther from the control oflice in sucha way, that the end station has a 'resistance unit similar to}??? of a value approximately equal to the total resistance-value of thetwo line conductors, plus the resistance value' of the line relays connected in the stepping line at all other stations. These units w ould then be reduced in resistance: value at stations b ter-s am ed .bv 'wa'm r n o ta t ear r, th Q fi with. t at station nearest th V ofiice having a unit with a resistance v'alue'equal only to the, line relaysiin the oflice, plus the line resistance between this station and the oflice.

During an indication cycle the line battery 013 in the control office cannot be connected to the line circuit because both relays OT and STR remain'do'wn. --It will be obvious that relay OT cannot pick up because of the fact that its pick-npcircuit remains open at back contact of relay OR, which relay remains up during a cycle of this class. A closed circuitbridge is plaicedacross the line conductors in the control tioning relay PCe to theleft. This circuit extends from (13+) code jumper 222 in its full line position,- front contact 223 of relay' IV}, back contacts 224, 225, 226 and 221 in series of stepping relays 2Y 3 V 4V and 5V respectively, conductor 228, back contact 2 2|; of relay FT winding of relay P0 and backcontact229 of relay FB to 1(CN) This circuit positions relay P0 during the. first "01? or conditioning period and is. eifective, to ,preselect the polarity to be applied to the line circuit ,duringthenext on? period. 'With; relay-RC positioned to the left, the

terminal of battery FB (connected to front.con-

tactl52:of"re1ay LO Vas above pointed out) extends -through contact 219 of relay P0 in its.

lefthand position, return line conductor I, back contact l3 of -relay.. OT,' back contact M of relay STR, front contact 92 of relay SA, front 7 contact l 5 of relay OR, back contact 5 of relay STR, back contact I! of relay OT, windings of'relays- HL and F, back contact I801 relay P, stepping line-conductor H, windings of relays ,HL ,and ;F resistanceR or contact.

2311 of. relay CGlin, its lefthand position :(as will be later explained), contact23l of relay PCP-in its lefth'andgposition', front contact I53 ofrelayf L0 1, back, contact 1540f relay STR conductor IZIL back contact I55 of relay E'I to the terminal of battery This current flows in sucha direction that relaysiF and fFf will bepositioned to thc right.

This positioning of contact I16 of relay-F at the field station is ineffective since contact I'II of relay F'I' is open. Positioning relay F in the control office to the right closes a circuit which extends from (B+), contact 93 of relay Fin its right hand position, front contact 30 of relay 0R, front contact 94 of relay FP, back contacts 95, 96, 91, 98 and I00 of stepping relays LV, 5V, 4V, 3V and 2V respectively, front contact IUI of relay IV, conductor I02 and upper winding of pilot relay IPT, to (B). Current in this circuit is effective to pick up relay IPT, after which it is stuck up over a circuit extending from front contact I03 of relay SA, conductor I04, front contact I05 of relay IPT and lower winding of relay IPT, to

In the event that code jumper 222 is connected in its alternate or dotted line position, then with relays IV and IV picked up and the line circuit energized, relays F and F are actuated to their left hand positions because relay PC has its contacts actuated to their right hand dotted positions over the above described circuit which now extends to (B) through jumper 222. This actuation of contacts 2I9 and 23I of relay P0 reverses the connection of battery F3 to the line conductors, so that the terminal of this battery is connected to the stepping line at the transmitting field station and the terminal is connected tothe return line at this station.

With relay F positioned to the left, the above described circuit leading to the upper winding of relay IPT does not energize this winding, because contact 93 of relay F in its left hand dotted position connects (B) potential to one terminal of the upper winding of relay IPT which has the same potential on its other ter-' minal.

With code jumper 232 connected in its full line position to (B) as shown in Fig. 3B, the circuit for positioning relay PC is completed on the second step and the contacts of relay PC are actuated to the right. This is effective to connect battery FB to the line conductors in such a direction that relay F in the control office is actuated to the left.

A circuit is now closed from (B), contact 93 of relay F in its left hand. dotted position and the above described circuit through contacts of the stepping relays, but now through front contact I00 of relay 2V and conductor I06 to the upper winding of relay 3PT.. Relay 3PT is not operated since it has the same potential connected to both terminals of its pick-up winding.

It will be obvious that should jumper 232 be connected in its alternate dotted line position, then the circuit to (13+) through this jumper would be effective to position relay P0 to the left on the second step, which would result in relay F being positioned to the right to close a circuit through its contact 93 in the right hand position which would be effective to pick up relay 3PT. l

The above examples indicate how the selection of one of two conditions, that is or polarity by means of a code jumper at the field station for each step, provides. means for registering this selection in the control oflice by picking up or leaving down a pilot relay for each step. It will now be explained how an additional selection of one of two conditions is obtained during each step of the system, resulting in a selection of any one of a total of four different conditions per step for registering a station in the control ofiice.

With code jumper 233 connected to (3+) as shown by the full line connection this jumper in Fig. 33, then when the first stepping relay IV is picked up, a circuit is closed for energizing relay CC which extends from (B+), jumper 233,

front contact 234 of relay IV back contacts 235, 236, 231 and 238 of relays 2V 3V 4V and 5V respectively, conductor 239, back contact 220 of relay FT winding of relay CC and back contact 240 of relay FP to (ON). This circuit positions relay CO to the left during the first"off or conditioning period. This is effective to preselect the strength of current to be applied to the line circuit during the next on period. With contact 230 of relay CC in its left hand position, resistance R is short circuited so that when the line circuit is next energized from the high potential battery FB at the end field station, sufficient current flows to pick up relays HL and HL. I

The picking up of relay HL during the transmission of indications is not effective. The actuation of relay HL in the control oflice closes a circuit from (B+), front contact II'I'I of relay HL, front contact 3I of relay OR, front contact I08 of relay FP, back contacts I09, III), III, H3 and H4 of relays LV, 5V, 4V, 3V and 2V respectively, front contact II5 of relay IV, conductor H6 and upper winding of pilot relay 2PT, to (B). This circuit is effective to pick up relay 2PT which establishes a stick circuit for itself by way of its lower winding, front contact II'I, conductor I I8 and front contact II9 of relay SA, to I In the event that code jumper 233 is connected in its alternate or dotted line position, then with relays IV and IV picked up, the line circuit is next energized with a low degree of current because the above described circuit to relay CC positions this relay to the right, which, by opening its contact 239, includes resistance R in the line circuit. This prevents the picking up of relay I-IL when the line is next energized, so that the above described circuit to relay 2PT extends through back contact III! of relay HL, to (B). Obviously, the application of the same potential to both terminals of the pick-up winding of relay 2PT results in this relay remaining down.

Jumper 241 is also capable of being selectively connected to (B) or (B+) so that relay CC is positioned to the right or left when the second step is taken, as determined by the connection of this jumper. This is effective to condition relay 4PT, which is selected by front contact II4 of stepping relay 2V when the second step is taken in the control ofiice.

With the code jumpers 222, 232, 233 and MI connected as shown in their full line positions, it is apparent that relays IPT and 2PT will be picked up and relays 3PT and 4PT will remain down. This combination is effective to register the station with which relay 6ST of Fig. 2A is associated, since the'circuit for this relay is completed from front contact I35 of relay 3V, (when the third step is taken), conductor I2I, front contact I22 of relay 2PT, back contact I23 of relay 4PT, front contact I24 of relay IPT, back contact I25 of relay 3PT. and winding of.

relay 6ST, to

Indications from registered station.--When the line circuit is energized after the station has been registered in the control office, indicationstoring relays IR, 2B. and 3R are selectively positioned in accordance with positions of polar contact. 93 of. relay F, by way'of front contacts-I30,

BI and I32 of 'relay S ;T.: LikewiseQadditional indication storing relays which may be connected to contacts I26, I21 andql28 of .-relay 6ST-may bef c onditioned in accordance with the position 'of; co'ntact I01 of relay HL. I This-occursafter the system of the present embodiment has taken its third: step; Since; the conductors leading from front contacts 98, 91, 96, I I3,'III and III] of. stepping relays 3V, 4V and. 5V areiused for conditioning these indication storing relays-in a manner similar to the conditioning of the pilot relays, it will .not be explained in detail how this resultjis accomplished; V Itlshould be mentioned, howeventhatthese indication storing relays are preferably of the magnetic stick type so that they. remain in their last actuated positions without the use of an independent stick circuit. Thereason for relay HLbeing slow to release willv now be explained. Assume that a magnetic stick indication storing relay is positioned on the third step by relay HL'being ;up. The-circuit for energizing such arelaymay be traced from (B+) .,'front contact I01 of relay HL, front con- 'tact 3| .of relay OR,'front contact I08 of relay backigcontacts I09, Illl and'III' of relays LV, 5V. and 4V respectively, ,frontcontact H3 of relay 3V, conductor I33, front contact I26 of relay; GST and winding of a magnetic stick relay (not shown) to (ON). I

Should relay HLrelease'before relay FP releaseswhen the line is next opened, contact IO'I' would reverse the current. in the above described circuit and set the magnetic stick relay to the opposite position to that called for by the code. By delaying the release of relay HL until sufficient time elapses to allow relay FP to restore,

2 the above false operation is guarded against.

'Should the detector track switch be occupied, relay vT would bedeenergized and the circuit would be closed from (3-), back contact 242 of relay T front contact 231 of relay 4V and the remainderofthe above described circuit to relay 0C right, which would result. in next energizing-the line circuit with a' low' current value so that relay HL would remain downto close a circuit from (B); by way of. its back contact I01 and front contact I I I of'relay 4V, conductor I29 and front contact l2'l of relayBST to a suitable indication storing relay for recording the posi- I tionofrelayT It is to be understood that indicating devices such as lampsor the like are connected to contacts of the indication storing relays for displaying to the'operator the-required indication.

' It is believed obvious how the position of relay taken care of.

WP may likewise be indicated in the control office by the transmission of ,codecombinations in amanner which has been throughly explained.

Likewise conductors 243, 244 and 245 may be connected to other contact devices for transmitting the positions of such devices to the control ofiice. a t l V I Plurality of stored start conditions.--In the event of several stored office and field start conditions, the communication system functions. to

send controls until all stored controls have been taken care of. After this, the communication system is used for the transmission. of indicationson separate cycles until they have been Assuming that there are several stored office and'field 'start conditions, there will be several storing relays in the control'of- 'fice picked up so that when relay CD of Fig. 2A

Is dropped at theend'of a'cycle, asimilar relay tactj'IZ of relay LV and This would position relay CC to the is picked'up to close a circuit similan gto that lease with'the exception of relay LV. ,RelayOT is restored to normal when, r elay SA d iQDs and opens its front contact 2|. a y ,y

Since relay LV is slow to release and since relay P is held energized until relay LVis released, the line circuit is maintained open for a comparatively long interval. The circuit for relays are releasedextendsfrom contact 65 of relay VP in its left hand position, (posi-; tioned thus when relay-5V closed its front contact 40);:upper windingof relay 1?, front icon:

front contact I3 of relay SAP,to().-

During this long .0 period, relay SA of Fig. 3A and relay SA of Fig. 1 are released.

Since the line circuit is open, relays SAP and SAP are'stuck up by means of a circuit which is. shown in full in Fig. 3A (similar at other field.

stations including the end field station), extending from contact I9I of relay F in its deenergized position, front contact I92 and winding ofrelay SAP to After relay'LVof.

Fig. 2B is released, relay P deenergizes and the line. circuit is closed, which places the-system in its normal or, period of blank condition The communication system now functions. as above described to transmit controls'as determined by the particular CD relay which is'picked up. A field station' -can not break in on the .line under this condition because relays similar to SAP must be down .to close back contact 204 for relays similar to S'I'R. to be picked up. With the system going intothe period ofblank withrelay SAP up and with relay STR in the con-. trol ofiice'picked'up, a high degree of current energizes the'line circuit to pick up relay HL With relay F actuatcdto its right hand position and relay HL picked up, the circuit is again closed which picks up relay 8A Relay F'I is likewise picked up'over the. previously described circuit and closes, at its front contact 202, the circuit for energizing relay SAP before this latter relay drops its contacts.

In. brief, the circuits-are so organized that as long as there are controls to be sent, the con= trol office starting relay 'STR is picked up at the end of each controlcycle when. relay SA" drops. The field-station starting relays similar to STR. are prevented from picking up at the start of the cycle even though there'are tions to be sent.

Should there be a plurality of field-stations with indications to transmit when there are no controls to betransrnitted, these stations transmit their. indications in rotation with th'e'sta tion nearest theend of the" line having prefer ence. I I

Lock-out between field stationsp-It' is believed that thelock-out feature'may be best under stood by assuming that two relays similar to relay CH of Fig. 3B are down at the same time,

with the system in its normal, or period of blank condition. It will be assumedthatrelay .CHl 7 5- i d e-1 energizing relay P after the first five stepping of Fig. 3B is located at the station nearest the end of the line. The operatio'nis the same whenmore than two relayssimilar to relay CH are down at the same time at thestart of a cycle' of operations, since only the station nearest the circuit is closed for picking up r'elay LO when relay SA picks up and, closes; its, front contact 2. This circuit has been previously described in detail.

The other relay similar to relay STR 'Which has been picked up, due to the other station having indications to transmit and which sta'' tion is located nearer the control 'office, is inef' fective to energize the look-out relay similar to relay L0 at this other station. This is because relay S'TR at the station nearest the end of the line opens, at its back contact I54 '(seeFig. 1) the stepping line conductor extending to ward the control ofiice, so that there isno energy applied to this line conductor for picking up-the lock-out relay at any other station. 7

When relay STR, drops at the end of the conditioning period, another relay similar to relay S'I'IR. at any other station'toward the control ofiice will not be up because both the pick-up,

and stick circuits of such other starting relays will be open at back contact 204 of relays similar to relay SAP at these other stations. This is due to the fact that .all, the relays; similar to relay SAP pick up during the conditioning period, before relay STR at the station nearest, the end of the line dropsto start sending im-{ pulses. e I V Since relay LO at the station. nearest the end of the line is the only one picked up under this condition, this station is effective to condition the line circuit by means of contacts 2I9, 23I and 230 of its relays PC and. CO flhe continuity of the line is established atback icontacts I52, I53 and I54 of the lookout and start relays at all other stations.

Having thus described one specific embodiment of a centralized trafiic controlling system,

it is desired to be understood thatlthe particular arrangements illustrated, and suggested are only typical of applicants invention and. xa intended to indicate the exact circuit design and arrangement necessary to carry out the features of the invention. For example, the line battery voltages specified at the beginning of the spec ification may vary to suit difie'rent conditions without departing from the spi'ritpf 'the' invention. This particular form has been selectedto facilitate in the disclosure rather thanto" limit the number of forms whichit may assume and it is further desired to be understoodthat various.

the amount of apparatus at,v each field station, a

all without in any manner departing from the spirit or scope of the present invention except" as limited by the appended claims. What I claim is:

1. In a remote control system, a control office,

a" plurality of field stations, a line circuit con-i necting said control oifice with said field sta'-' tions, means for energizing said line circuit from a source of current at a first one of said field stations, means at said control office for pe-,

riodically opening said energized line circuit to provide aseries of impulses, means at a second one of said field stations for selectively reversing the fiow of impulse current over said line circuit between said second station and said control officefor each impulse of said series, means at said second station for selectively varying the intensity of each impulse of said series, and means at said control office responsive to the direction of current flow and the intensity of each impulse of said'series.

2. In a remote control system, a plurality of I locations including a control office and a plurality of field stations, at line circuit connecting said locations, means for intermittently and distinctively energizing said line circut from a source o'f icurrent at one of said locations to provide a series of distinctive impulses, means for intermittently and distinctively energizing said line circuit from a source of current at another of said locations to provide an additional series of distinctive impulses, means controlled by the si multaneous energization of said line circuit from a plurality of said locations for determining the source otcurrent used for impulsing'said line circuit, and means controlled by said series of impulses for transmitting messages between said le'cations. I Y

,3. Ina remote control system, a plurality of locations including a control ofiice and a pluralitys of field stations, a normally energized line circuit-connecting said locations, means for intermittently and distinctively energizing said line, circuit during an operating cycle from a source of current at one of said locations for providing a first series of distinctive impulses, means for intermittently and distinctively energizing said line circuit during an operating cycle from. a source of current at another of said locations for providing a second series of dis-,

tinctive impulses, means controlled by the simul taneous energization of said line circuit from both of said sources of current for allotting said 7 first series of impulses to said cycle, means controlled by initially deenergizing said line circuit for allotting said second series of impulses to said cycle, and means controlled by said series of impulses for transmitting messages between said oc tio s- I v 4. In a remote control system, a control oflice, aplurality of field stations, a line circuit connecting said control ofiice with said field stations, means for transmitting a plurality of series of current impulses of variable polarity in one direction over said line circuit, means for transmitting a plurality of series of current impulses of yariable intensity in another direction over said line circuit, means for preventing the transmission of a series of variable intensity impulses as long as a condition exists requiring the transmission of variable polarity (impulses, and means controlled by said series of impulses for transmitting messages between said office and said stations.

' 5. In a remote controlsystem, a plurality of locations including a, control ofiice and a field station connected by a line circuit, a source of current at each of said locations, means including the source of current at said field station for normally energizing said line circuit to a low degree means including both of said sources of cur-,

rent for initially energizing saidline circuit to a high degree means for initially de-energizing said line circuit, a-control code transmitter in said ofiice and an indication codetransmitter at said station, meanscontrolledbyfsaid control 7 r and said indication code transmitters when ren- V dered effective for transmitting control and indication codes respectively between said locations, means responsive to the initial energization of said line circuit to a. high degree for rendering said control code transmitter effective, and means I responsive to the initial de energization of said ,line circuit for rendering saidrindication code transmitter effective.

' 6. ma remote controlsystem, a plurality of locations including a control oflice-and a field station connected by a linecircuit, means for nor mally energizing said line circuit to a low degree, means for initially energizing said line circuit to a high degree, means for initially de-energizing said j line circuit, a control code transmitter in said office and an indication code transmitter at said station, means controlled by said control and said indication code transmitters when rendered efifective' for transmitting control andindication codes respectively between said locations, means responsive to the initial energization of said line circuitto a high degree for rendering said control code transmitter effective, means responsive tothe initial de-energization of said line circuit for rendering said indication code transmitter.

effective, and means for rendering said indication code transmitter ineffective as long as a condition exists requiring the transmission of both a step-by-step mechanism at said one location operable through a separate cycle for each of said series of impulses, means controlledbysaid mechanismi'or selecting two local channel circuits for, each step, means for.causing saidmechj anism to take one step for each time space be- 'twe'n successive impulses of a series, means at another of said locations for energizing said line circuit with current of variablegpolarity and variable degree at each step, means for distinctively energizingone of said channel circuits in accordance with the polarity of energization of said line circuit for thatstep, and means for distinctively energizing the other of said channel circuits in accordance with the degree of energization'oi saidline circuit'for that stepf 8. In a remote control system, a plurality of locations connected'by a stepping line; means at one of said locations for applying a plurality of time spaced impulses to said stepping line, a step-by-step mechanism at said one location operable through a separate cycle m each of said mechanism forselecting two local channel cir.-' cuits for each step, ,means for causing saidmechanism to take one step for each 'timespace between successive impulses of a series, an electroresponsive device for each of said channelcircuits, -means at another of said locations for energizing said line circuit withcurrent of va'-' riable polarityfand variabledegree at each step, means iorjdistinctively energizingone of saidchannel circuits in accordance with the polarity of energization of said line circuit for thatstep,

means for distinctively energizing the other of I said channel circuits in accordance with-the de,-

greeof energization of said line circuit for that step,1and means responsive to. the distinctive,

energization of thetwo channel circuits for each 9. In a remote control system, a pluralityofl locations connected by a line, means at one of said locations for applying a series of time spaced current impulses to said line, means at another 1 of said locations for varying the direction-of" impulse current flow over said -line',means1at another of said locations-for varying the intensity I of impulse current flow over said line, step-Icy.-v

step mechanism atsaid one location operated one,

step for each time space between impulsesforQ preparing a plurality of'local channel circuits for each step, and means for energizing'the'channel circuits for each step in accordancewi'th the directioniof impulse current flow for thatis tepandlin accordance with the intensity of impulse current flow for that step. o a l '10. In a remote control system, acontrol-oflice and a plurality of distant stations interconnected. by a line circuit,smeans includinga source of our- 7 rent at the most distant station of said plurality for normally energizing said line circuit, a trans-I- mitter at each of said stations for transmitting, messages from theassociated station to saidofiice when rendered efiective meansat acalling station for de-energizing said linecircuit, meansresponsive to the de-energization of said'linecircuit for efiecting the energization of. only that por:

tion of said line circuit extending between said calling station and said most distant stationand 'meansresponsive to the energization of said por tion of said line circuit for rendering said-trans-i f mitterefiective N 11. In aremote control system-,5tenements and a plurality of distant stations interconnected by alineQcircuit, means including" asource'ofv current at the most distant station of said pluralityjfor normally energizing said line circuit, a transmitterateach of saidv stationsior transmittingjmessages from the associated station to 7 said office when rendered effective, a loch-out relay at each of said stations, means at acalling station for de-energizing'saidline circuit, means' 7 responsive to the de-energization of said line cir cuit 'for eflecting the energization of only that portion of said line circuit extending between said calling station and said mo'st distant station, means responsive to the energization of said portion of said line circuit'for operating lock-out relay, and means responsive tothe op,-"

eration' of said lock-out relay for rendering said transmitter efiective.

4 12. In a remote control system, a control of-;-

fice and a plurality of stations interconnected by a normally energized line circuit, a transmitter at each of said stations effective totrans- Series of impulses, means controlled-ebb, said, mit signals from the associatedstationtothe control office when actively associated with said mitter with said line circuit, means at a first station having signals to transmit for deenergizing said normally energized line'circuit, means responsive to: the de-energization of said line circuit for energizing only that portion of 'said line c'ircuit extending from said first s ta' tion to stations more distant from saidiofflca and means responsive to the energization of said portion of said line circuit for causing said lockout relay to actively associate the associated transmitter with said line circuit.

13. In a remote control system, a control of fice and a plurality of stations interconnected by a normally energized line circuit, a transmitter at each of said stations elfective to transmit signals from the associated station to the control ofiice when actively associated with said line circuit, a lock-out relay at each of said stations for actively associating the associated transmitter with said line circuit, means at a first station having signals to transmit for de-energizing said normally energized line circuit, means responsive to the de-energization of said line circuit for energizing only that portion of said line circuit extending from said first station to stations more distant from said ofi'ice, means responsive to the energization of said portion of said line circuit for causing said lock-out relay to actively associate the associated transmitter with said line circuit, and means at a second station more distant from said ofiice than said first station for rendering the look-out relay at said first station ineffective to actively associate the associated transmitter with said line circuit and to cause the look-out relay at said second station to actively associate the associated transmitter with said line circuit.

14. In a remote control system, a control office, a plurality of field stations, a line circuit connecting said ofiice with said stations, means for energizing said line circuit from a first source of current in said office, impulsing means and pole-changing means in said ofilce for intermittently interrupting and pole-changing the energization of said line circuit from said first source of current to provide a series of variable polarity impulses, means for energizing said line circuit extending from said ofiice to all of said stations from a second source of current at a particular station, means at each station for Varying the degree of energization of said line circuit while it is being impulsed by said impulsing means and energized from said second source of current to provide a series of variable intensity impulses, and means for allowing the energization of the line circuit from only one of said sources during the impulsing of said line circuit.

15. In a remote control system, a control office, a field station, a line circuit connecting said oflice with said station, one means for energizing said line circuit from a first source of current in said office, impulsing means and pole-changing means in said ofiice for intermittently interrupting and pole-changing the energization of said line circuit from said first source of current to provide a first series of variable polarity impulses, another means for energizing said line circuit from a second source of current at said station, means at said station for varying the degree of energization of said line circuit while it is being impulsed by said impulsing means and energized from said second source of current to provide a second series of variable intensity impulses, means at said station for pole-changing the energization of said line. circuit from said second source of current to render said second series of impulses of variable polarity, and means rendering effective only said one means or said another means at any one time.

16. In a remote control system, a plurality of locations including a control office and a plurality of field stations, a line circuit connecting said locations, transmitting means, means for operating said transmitting means through operating cycles, control means for intermittently and re.- versibly energizing said line circuit during an operating cycle from a first source of current at said oflice for providing a first series of polar impulses, indication means for intermittently and distinctively energizing said line circuit during an operating cycle from a second source of current at one of said stations for providing a second series of distinctive impulses, means at said office for selecting the polarity of each of said first series of impulses in accordance with predetermined outbound code calls, means at each of said stations for selecting the current intensity of each of said second series of impulses in accordance with predetermined inbound code calls, means at said one station selectively responsive only to said first series of impulses, means at said ofiice selectively responsive only to said second series of impulses, and means effective at the start of a cycle for rendering said control means superior to said indication means.

17. In a remote control system, a plurality of locations including a control ofiice and a plurality of field stations, a line circuit connecting said locations, transmitting means, means for operating said transmitting means through operating cycles, control means for intermittently and reversibly energizing said line circuit during an operating cycle from a first source of current at said ofiice for providing a first series of polar impulses, indication means for intermittently and distinctively energizing said line circuit during an operating cycle from a second source of current at one of said stations for providing a second series of distinctive impulses, means at said oflice for selecting the polarity of each of said first series of impulses in accordance with predetermined outbound code calls, means at each of said stations for selecting the current intensity and the polarity of each of said second series of impulses in accordance with predetermined inbound code calls, means at each of said stations selectively responsive only to said first series of impulses, means at said ofiice selectively responsive only tosaid second series of impulses, and means efiective at the start of a cycle for selectively rendering said control means or said indication means efiective during such cycle.

WILLIAM D. HAILES. 

